The operation of OLEDs is based on the phenomenon of electro-luminescence, wherein the emission of light results from the action of an electric field or a current flowing through a given substance. In OLEDs, such phenomenon consists in injecting electric charges into an extremely thin layer of an organic material (usually about 100 to 200 nanometers thick). The light thus comes from the emission of a photon generated by the recombination of an exciton (electron-hole pair), within the emitting polymer layer.
Researches on the production and marketing of organic semiconductors, have recently accelerated. Such technologies, initially intended for professionals, now find more and more general public applications, particularly in the field of domestic lighting.
Through their various applications, OLED devices should also take advantage of the development of printed electronics, which is expected to significantly grow in the coming years.
OLEDs could spread for producing small screens integrated in phones, cars, cameras, MP3 players, as well as television screens or billboards.
Today, however, the degradation of such organic devices remains a critical issue. The extreme sensitivity of the organic materials in the presence of water and oxygen imposes a production in an inert atmosphere and a final encapsulation (as is the case for OLED screens, for example).
Currently, electrodes are supplied through portions not covered by the encapsulation of the OLED, and thus induces complicated and, therefore, expensive manufacturing processes with no perfect sealing guaranteed.
Several approaches for electrical connection to light emitting devices have thus been considered. Among these, one solution consists in encapsulating the stack comprising the organic layer using a cover. A metal layer then covers said cover, thus protecting the OLED system from possible ingress of water and oxygen into the system. This approach is mentioned in the patent application EP1 120838A1. In this solution a second perforated cover is used, which is placed on the OLED device, with said OLED device already comprising a first cover. A disadvantage pointed out by this study is the mechanical type contact existing between the encapsulated OLED device and the second cover which may generate a defective contact. On the other hand, the method described is long, and the final OLED device lacks compactness.
The present invention makes it possible to solve all or at least some of the drawbacks of the current techniques.